-
You can download the Land Registry data from here https://www.gov.uk/government/statistical-data-sets/price-paid-data-downloads to make it reasonably quick to search through the surrounding area. When I remortgaged last year and needed a value I just looked at two or three streets either side and that gave enough options to take a guess at the value.
If you do buy the freehold then it does give you options for extensions, loft conversions, etc if that is a consideration. Obviously partly depends on your lease.
aggi-
Think my lease is relatively favourable in terms of loft conversions. The loft space is definitely included in the demise and I'm solely responsible for maintenance of the roof. Would obviously still require consent - which would no doubt have a cost associated - but it's my understanding that the landlord 'can't unreasonably refuse' it.
Brun
That's what I meant by finger in air/zoopla option. I'm on London's famous Harringay Ladder so there's no end of similar-ish properties.
Thinking more about this, the accuracy will only affect the quote so isn't terribly important in the grand scheme of things? The actual cost will be determined by more formal valuations in due course.